Stabilizers for photographic silverhalide emulsions



Patented July 6', 1.948i

UNITED STATES STABILIZERS FOR PHOTOGRAPSHIC SILVER- HALIDE EMULSIONNewton Heimbach and Walter Kelly, Jr., Binghamton, N. Y., assignors toGeneral Aniline & Film Corporation, New York, N.. Y., a corporation ofDelaware Application April 23, 1946, Serial No. 664,254

This invention relates to 1,3bis[3amino-1,2,4- triazole] oxypropenes, toa method for their preparation, and to photographic silver-halideemulsions containing the same.

It is known in the art that light-sensitive emulsions, such as gelatinsilver-halide emulsions, have a decided tendency to fog. The fog may beof two types, namely, yellow fog and chemical (gray) The yellow fog,sometimes referred to as color fog or dichroic fog, is essentially acolloidal deposit of silver, the color intensity and general appearanceof which are determined by the minute particle size and degree ofsubdivision. The fog is chiefly yellow in color and is most apparent inthe lighter portions of a negative. The color may vary, however, and thecolloidal silver particles may, for example, appear green by reflectedlight and yellow or red by transmitted light. The so-called chemicalfog, or gray fog, on the other hand, is the more common and is formed ina number of ways. It may be caused by premature exposure, by excessiveripening' of` the emulsions, or by the storage of the film, particularlyat high temperatures or for unusually long periods of time.

It is an object of the present invention to provide 1,3-bis[3-amino-1,2,4triazolel -oxypropenes useful as stabilizers forsilver-halide emulsions.

Another object oi this invention is to provide a process of preparingsuch 1,3-bis[3-amino-l,2,4- triazolel -oxypropenes A further object isto provide 1,3-bis[3-amino 1,2,4-triazolel-oxypropenes as stabilizers orfog inhibiting agents which tend to prevent the formation of chemicalfog in light-sensitive sil- Ver-halide emulsions,

A still further object is to provide `1,3-bisl3-amino-1,2,4-triazolel-oxypropenes as stabilizers or anti-fogging agentsfor light-sensitive silverhalide emulsions, which do not lower thesensitivity of the emulsion, an-d which increase its stability.

Still further objects and advantages will appear from the followingspecification.

We have found that the above objects are accomplished by condensing a-keto ester or anilide thereof, with a 3-amino-1,2,4triazole. Theresulting condensation product is characterized by a structurecorresponding to the following general formula:

11 Claims. (Cl. 95-7) 2 wherein R isv hydrogen or an alkyl group, e. g.,methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl,teit-butyl, amyl, and the like, R1 is an alkyl of the same Value as R,aryl, e. g., phenyl,r

- o, m-, and p-tolyl, naphthyl, diphenyl, etc.,

aralkyl, e. g., benzyl, methylbenzyl, ethylbenzyl, and the like, R2 iseither hydrogen allyl, or an alkyl of the same value as R.

The method for the preparation of 1,3-bis[3amino-1,2,4-triazolel-oxypropenes consists of condensing l mol of a-keto ester or anilide thereof, of the following general formula:

wherein Rs is of the same value as R1, R4 is of the same value as R2,and R5 is an anilino or alkoxy radical, e. g., methoxy, ethoxy, propoxy,butoxy, amoxy, heXoXy, heptoxy, octoxy, and the like, with 2 mols of3-amino-1,2,ltriazole of the following general formula: v

/N\ Re-(IJ/ NH N= NH2 wherein Re is either hydrogen or an alkyl group,e. g., methyl, ethyl, propyl, butyl, and the like.

Suitable -keto esters and anilides thereof are, for example, ethylacetoacetate, ethyl benzoylacetate, ethyl a-ethyl acetoacetate, ethyla-allyl acetoacetate, ethyl toluylacetate, ethyl propionylacetate, ethylbutyrylacetate, ethyl valerylacetate, ethyl acetoacetanilide, ethylbenzoylacetanilide, ethyl a-ethyl acetoacetanilide, ethyl a-alylacetoacetanilide, ethyl toluylacetoacetanilide, ethylpropionylacetoacetanilide, ethyl butyrylacetoacetanilide, ethylvalerylacetoacetanilide, and the like.

As suitable 3-an1ino-1,2,4triazoles may be mentioned,3-amino-1,2,4triazcle, 3amino5 methyl -1,2,4- triazole, 3 -amino-5-ethyl-1,2,4- triaz'ole, B-amino -5- propyl -l,2,4 triazole, 3-amino-5-butyl-1,2,4-triazole, B-amino -5- amyl- 1,2, l-triazole, and thelike.

The rcondensation [between the -keto ester or anilide thereof, and the3-arnino-l,2,4triazole is carried out by heating =the reac-tioncomponents at a temperature ranging from -160 C., in the presence of asuitable solvent such as nitrobenzene, for a period oi time ranging from10 minutes to 2 hours. The iinal product either precipitates or isremoved by diluting with an aromatic hydrocarbon, such as,v for example,toluene, chlorobenzene, cyclohexane, cyclohep.

3 tane, cyclooctane, benzene, o, m, and p-Xylene, ethylbenzene,1,2,4-trimethylbenzene, propylbenzene, l-ethylmethylbenzene, or an 05W-genated solvent, e. g., ether, acetone, ethylmethyl ketone, diet-hylketone, dimethyl ketone, propyl ketone, allylacetonecmesityl oxide,dioxane, and= the like, and -iecrystallized from water; Instead ofheating the reaction components, the reactants may be allowed to standin a cold, aqueous, alk

aline solution such as, for example, a 5-207% aque-` ous solution ofsodium or potassium hydroxide-l for several days at room temperaturaAfter standing for several days atrroomntemp'eratm'eif the reactionmixture is dilutdi-With'aboutan equal Volume of Water and warmedslightly torcedissolve the precipitated lproduct. To this solution asufficient quantity of cold-glacial yacetic-.2`

acid is added in order to neutralize the alkali,

and after chilling in an ice-bath, the productie' filtered off andWashedseveral times with cold water andnecrystallizedifromboilingzwater.

'Ile'lr 3-aniir1'o-1,2,4tria2oles. :Fand: the -keto estersandanilidesthereoflarewelliknown to the artfand thezmeth'ods for their.`preparation meed notllceF4 described herein; r

Speci'ccompounds."Which have been .prepared inlaccordaiicelwiththelabveprocedures,V with their formulas, are asrfollowsfz CH3 03H5 o amenacen-oC-CHzoH'or CH3 CH3 O Example 1I '1'0"15` cc. of nitrobenzene, 0`.1' incl(8.4' grams) of"3arnino1,2,41-triazole'and U.05`1'n'ol(8.5 grams) of'ethyl a-allyl acetoacetatelwereadded andl the mixtureheatedto'15U-,160''LC., foi 1 hour.y The reaction mixture -was cooled toroomtemperature andl theproduct precipitated by' the addition of ether.`Tlieprecipitated product was washed s'evieral'timeswitlfi'V ether andrecry'stallied from Wa-- One-tenth mol (854;y grams) of 3arnino1l,2,4trlazole is dissolved in 156e.- of- Water andthemix# ture cooled toroom-temperature.- To thislsolu-v tion 0.1 mol.-(13grams)offethyl,acetoacetateis added. After standing for lvminutesyacoldsolution of 4 grarnsfof NaCbH-in 10 ccs-of- Water` isaddedslowlywith external cooling-to *keep-.the mixture approximately atl roomf temperature. After standingA 2 days.- at roomftemperature, the

mixture isdilutedto 40 ccVandWarmed/slightly;

to redissolve the precipitated product. Six grams: of coldiglacial`acetic'acid is their added,- andf after chilling in anicefbathftheproductislteredoff: and Washedvwith a few cc.-offcoldwaterandrecrystallized fromtboiling AWater.-

CH3-C To 15 cc. of nitrobenzene, 1 mol (9.8 grams) of3-amino-5methyll,2,4triazole and 0.05 mol (6.5 grams) of ethylacetoacetate were added and the mixture heated to 15G-160 C., for 1hour. The reaction mixture was cooled to room temperature and theproduct isolated |by diluting with ether and recrystallizing from water.

Example III was repeated with the exception that 9.6 grams of ethylbenzoylacetate was substituted for 6.5 grams of ethyl acetoacetate.

In the preparation of emulsions containing the stabilizers as aboveprepared, a solution of the stabilizer in a suitable solvent, such asalcohol or an alcohol-water mixture, adjusted to a neutral or slightlyalkaline pH, i. e., pH '7.5 to 10, is made up and the solution mixedwith the emulsion at any point during its preparation, but preferablyduring ripening or just prior to coating in concentrations varying from25 mg. to 500 mg. per liter of emulsion. The `actual concentrationemployed will depend upon the type of emulsion used and may varysomewhat with the particular compound employed.

The method of testing the stabilizers employed in the following examplesconsists of coating two film strips, such as cellulose acetate, with thesame emulsion, one with and one without any stabilizer, storing theemulsions in an incubator for six days at 50 C., then exposing,developing, fixing, and washing the same under standard conditions. Thefog density or -blackening produced in the unexposed areas in the twoemulsions is then measured in a transmission densitometer of standardtype.

The following examples will serve to illustrate certain ways in whichthe 1,3-bis[3-amino-l,2,4 triazolel-oxypropenes of our invention areapplied as stabilizers for silver-halide emulsions, but are not to beconstrued as limiting the invention.

Example V A photographic film coated with an ordinarygelatin-bromoiodide `emulsion of normal speed and contrast ondevelopment under standard conditions, after incubation for six days at50 C., gave a fog of 0.28 density. Another film coated with the sameemulsion containing an addition of 100 mg. of the compound of Example Iper 1000 cc. of emulsion, equivalent'to about 50 grams of silver-halide,and developed under the same conditions, after the same incubation, gavea fog of only 0.06 density.

Eample VI Example V was repeated with the veXcep-tion that an equivalentquantity of the compound of Example II was substituted for the compoundof Example I. The results obtained were almost identical with thoseobtained in Example V.

Ea'ample VII Example V was again repeated with the exception that 75 mg.of the compound of Example the emulsion containing the compound of Example III gave a fog of only 0.1.

Further experiments have shown that emulsions containing stabilizers inaccordance with our invention have not only improved keeping qualities(i. e., a reduction in thefog produced by incubation or by longstorage), but have-greatly `diminished and, in some cases -completelyeliminated changes of vspeed to which some emulsions are susceptible.

The stabilizers, which we have prepared and employed, may be used invarious kinds of emulsions. In addition to being useful inorthochromatic and panchromatic emulsions, they may also be used innon-sensitized emulsions and -X-ray emulsions. If used with sensitizingdyes they may be added to the emulsion before or after the dyes areadded. The dispersing agents for the silver-halides may be gelatin orother colloid such as water-soluble cellulose derivatives, e. g.,hydroxy ethyl cellulose, methyl cellulose, carboxy-oxy-cellulose, lowacetyl value cellulose acetate, and the like. The stabilizers may alsobe employed in gelatin or other colloid, such as polyamides or a mixtureof gelatin with a, polyamide as described in United States Patent2,289,775; polyvinyl alcohol and `ielling compound as described inUnited States Patent 2,249,537; polyvinyl acetaldehyde acetal .resinsand partially hydrolyzed acetate resins described iny United StatesPatents 1,939,422 and 2,036,092; cellulose derivatives, e. g., cellulosenitrate, cellulose acetate, the lower fatty acid esters of celluloseincluding simple and mixed esters, ethers of cellulose, and the like, asan under or overcoat for the emulsion, or as a backing layer for thesupport. Moreover, they may be incorporated in the support for thesensitive emulsion layer or in an intermediate layer between thesensitive emulsion layer and the support, such as the baryta coatingcommonly used in photographic papers, or they may be incorporated in aprotective layer coated upon the emulsion surface, or the otherwisenished photographic material may be bathed in an alcohol oralcohol-water solution containing the stabilizer.

In the accompanying drawing the various iigures are enlarged sectionviews of photographic materials having anti-fogging layers madeaccording to our invention. y

As shown in Figure 1, the support I', which may be of any suitablematerial such as glass, cellu-l lose ester, synthetic resin, or paper,is provided with an anti-fogging layerl 3, containing one of the 1,3-bis[3-amino-1,2,4triazolel-oxypropenes referred to above. The lightsensitive emulsion layer 2 is attached to the anti-fogging layer 3.

Figure 2 illustrates a similar material in which the support I is coatedwith a light-sensitive emulsion layer 2, and on the latter side there isprovided an anti-fogging layer 3 containing one of said 1,3-bisi3-amino-1,2,4triazolel-oxypropenes.

Figure 3 illustrates a lm or plate of which the support l bearson oneside the light-sensitive emulsion layer 2, and on the other side anantifogging layer 3 containing one of said 1,3-bis[3amino-1,2,4triazolel-oxypropenes `Figure 4 illustrates a lm, plate, orpaper of which the support I is provided with the lightsensitiveemulsion layer 2 containing as an antitriazole] -oxypropenes Since: the;Plasencia, off these` new compounds tenl toprevent; chemical, fog`whether they. are

in; rpo ratedil directly: into the emulsion, added to a. separatesurface orvsubstratum layenitzis understood, that. the term.photograplrno matei'ialasempioyed herein and in .the appended, claims,is usedfin a generic sense todnoludefeach.

of, thesepossible: applications;

Vaw. moeiiicationsl of` thisv invention will;

OCQulJ--O .13.1.2,1'591'18skilledV in theart andits, theresfcre,understood thatr the patent.` grantedshall;

only be limited by the appended claims..

We claimi.

1.y Af photographic material .comprising a base andxa..lightsensitivesilverfhalide emulsion care riad-thereby, said photographie. materialcontain.- ing, in .foginhibiting amount, a .compound of the general:formula:

wherein R is a` member selected from the class consisting Qf hydrogenand alkyl groups, R1 is a. member selected from the class consisting of'alkyl; arylanciaralkyligroups, and R2 is a memberselected from, theclass consisting of hydrogen.. ,allylzand 'alkyl f groups.

2': A- photographic material comprising a base anda light-sensitivesilver-halide emulsion carriei thereby, saidphotographic materialvcontaining,x` in fog inhibiting amount, a compound for the formula:

CH3 CaHs 0 3i..A.-.chetceraphic material 'comprsne abase.

and.. .flight-,sensitive:silverfhalide emulsion carreQ-thereb-y., said.nhotoeraphiemanai .centaine v f-,Oe nhbitifl.e;A aeomnound .ofthe H-c\ l/CH- N? r\f11frqi\iT =N.r

4; A photographicmaterialcorriprising a base and a light-sensitivesilver-halideemulsion oarriedjihereby,saidphotographic materialcontaining-,i n foginhibitingamount, a compound of lthe formula-zCHifllf 5.i A; llctcgranhic material, `cfilfrliufisi.ne as. base,-V

whereinR, is av mjen'ilzier-selectedA from the -class consistingofwhydrogenandv-alkyl groups, Riis a sar member: selected: from thelclass" f'zonsisting.I of alkyl, aryl andvaralkyl groups, andR2 isamember selectedfromthe class consisting oft hydro.- gen, ailyl, andalkyllgroups.

6.v AV photographic .material comprising a base, and a light-sensitivesilverhaiide emulsion containing, in fog inhibiting amount, a compoundof the formula:

7. A photographic'materialcomprising a base, and a lightvsensitivesilver-halide emulsion containing, in foginhibiting amount, a compoundof the formula:

\N=l-NH1. HQN.-C=N

10. A' photographic gelatine silver-halide, emulsion containing fromabout25 mg. to about 500 mg.- per `liter of emulsion of a compoundof'theformula:

N--C--NHz HzNC=N y 1l. A photographic gelatino silver-halide emulsion`containing,from about 25 mg. to about 500 mg, p enliterof emulsion ofacompoundf the probableformula:

Then following,references are. of record in the file of. thispatenti,

UNITED STATES-ii PATENTS L Name., Date I. Matthies et a1.` May 13,' 1930Number

